spec: remove most §links for the now more common in-text links
spec: remove most §links for the now more common in-text links

Also:
- more consistenly use "xxx" statement rather than <code>xxx</code> statement
- fix/remove unnecessary links

R=golang-dev, r
CC=golang-dev
https://codereview.appspot.com/7821050

wesolows/golang,firebitsbr/golang-old,wesolows/golang-old,wesolows/golang,firebitsbr/golang-old,wesolows/golang,wesolows/golang-old,wesolows/golang-old,wesolows/golang-old,firebitsbr/golang-old,firebitsbr/golang-old,wesolows/golang,wesolows/golang-old,wesolows/golang,wesolows/golang,firebitsbr/golang-old,firebitsbr/golang-old,wesolows/golang-old,wesolows/golang-old,wesolows/golang,firebitsbr/golang-old,firebitsbr/golang-old